Composite laminate and method of producing a composite laminate

ABSTRACT

The present invention provides a composite material including a substrate layer, a knit porous layer intermixed within the substrate material, and a thermoplastic layer disposed upon the porous layer. The porous layer is at least partially disposed within the thermoplastic layer. The present invention also provides a method for forming the composite material including the steps of: providing a substrate layer, providing a porous layer disposed on the substrate layer, providing a thermoplastic layer disposed on the porous layer, applying pressure and vacuum to mechanically interlock the thermoplastic layer with the porous layer; and bonding the porous layer to the substrate layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/709,550 filed Feb. 22, 2007, which is a continuation-in-part of U.S.Pat. No. 7,273,644 issued on Sep. 25, 2007, which iscontinuation-in-part of International Application No. PCT/US2001/03561,filed Feb. 2, 2001, which claims the benefit of U.S. ProvisionalApplication No. 60/225,137 filed Aug. 14, 2000. The disclosures of theabove applications are incorporated herein by reference.

FIELD

The present disclosure relates generally to composite materials and tomethods of manufacturing the composite materials. In particular, thecomposite material of the present invention includes a thermoplasticmaterial having a relatively low coefficient of friction such asultra-high molecular weight polyethylene (UHMWPE) which is bonded by useof a porous material such as a fibrous mat to a substrate.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

While not limited in any way to food processing equipment, the presentinvention was conceived in part to meet a need in the industry.Heretofore, food processing equipment has largely been manufactured fromstainless steel due to its known strength and relative durability. Ithas been discovered that at least certain pieces of stainless steel foodprocessing equipment, particularly those involved in high temperatureand vibration environments, tend to be susceptible to stress crackingover time. Further, the cleaning of such food processing equipmentmanufactured from stainless steel is unnecessarily labor intensive,often requiring at least two people.

In contrast, the composite material of the present invention isresistant to stress cracking, is relatively easy to clean, and tends tobe lightweight (generally at least 50% lighter than all stainless steelembodiments). Further perceived advantages include less sticking of foodcomponents, reduced noise associated with the product, and speedyassembly and disassembly times, among a host of other advantages.

SUMMARY

The present invention relates to composite materials having a firstlayer including a thermoplastic material having a static coefficient offriction of less than about 0.25 at 23° C. as measured against chromiumplated steel, a second layer comprising a porous material to which thefirst layer is intimately bonded, and a third layer which is asubstrate.

The present invention also relates to methods of manufacturing thecomposite materials for specific applications. The method generallycomprises the steps of:

-   -   a) providing a substrate;    -   b) applying a porous layer onto the substrate;    -   c) applying a thermoplastic material having a static coefficient        of friction of less than about 0.25 at 23° C. over the porous        layer; and    -   d) joining the materials under vacuum, pressure or a combination        of vacuum and pressure.

Further details and advantages of the composite according to theinvention, of the method and of the device, are described with referenceto the embodiment illustrated in the drawings.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is an exploded view of the preferred embodiment of the invention;

FIG. 2 is a cross-sectional view of a preferred embodiment of thecurrent invention;

FIG. 3 shows an exploded view of one embodiment of the material of thepresent invention;

FIG. 4 is an alternate embodiment of the current invention;

FIGS. 5 a-5 e depict a method of manufacturing the material of thecurrent invention;

FIG. 6 is a typical autoclave set-up as is known in the art;

FIG. 7 is a detail of the vacuum bag system for use in the autoclave ofFIG. 6, for producing the material in the current invention;

FIGS. 8-10 depict the vibratory pan assemblies as used in the foodindustry utilizing the composite of the present invention;

FIGS. 11 and 12 represent coating drums using the composite of thepresent invention;

FIG. 13 represent an elevator lift bucket using the composite of thepresent invention;

FIGS. 14-16 represent the scale hoppers using the composite of thepresent invention;

FIGS. 17-19 represent a blending hopper using the composite of thepresent invention;

FIGS. 20 and 21 represent bagging hoppers using the composite of thepresent invention;

FIG. 22 represents a static reduced UHMWPE NuCon demount rotary valveusing the composite of the present invention;

FIGS. 23-25 represent a raisin let down transition using the compositeof the present invention;

FIGS. 26-27 represent the formation of support structures;

FIG. 28 represents the method of forming a knit porous layer;

FIGS. 29 a-29 c represent the porous layer shown in FIG. 28; and

FIGS. 30 a and 30 b represent a water craft utilizing a compositematerial shown in FIG. 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

FIG. 1 depicts the components of a composite 26 in accordance with theteachings of the present invention. Shown is a substrate 27 formed froma thermoformed epoxy, preferably a reinforced thermoformed epoxy madefrom a two part epoxy. By reinforced it is meant that the epoxy resinincludes fibers such as glass, synthetic fibers such as KEVLAR®, carbonfibers, metallic fibers, or particulate by way of non-limiting example.The fibers may be in the form of a woven mat, individual fibers inchopped or unchopped form, or combinations thereof. A particularlyuseful woven mat is a 3×3 twill carbon fiber reinforcement layer,preferably 3 k twill 1161 woven fabric, available from Amoco. Acommercially available two part epoxy substrate 27, which is useful inaccordance with the teachings of the present invention, is made of West(brand) Epoxy 105 Resin, utilizing a 205 Fast Hardener from GougeonBros. Inc, Bay City Mich., with a 3×3 Twill Carbon Fiber reinforcementlayer. Under a highly preferred embodiment, the substrate 27 will be amulti-layer construction or designated by reference numerals 27 a and 27b.

The composite 26 also includes a porous layer 28, which is in the formof a fibrous mat. It is envisioned that it is possible that the reactioncuring the epoxy resin phase of the substrate 27 will be an exothermicreaction. The heat produced by this reaction may assist in the formationof the bond between the thermoplastic layer 29 and the porous layer 28.The fibrous mat can be constructed of glass, steel, or natural andsynthetic fibers, by way of non-limiting example. While the porosity oflayer 28 may vary depending on the ultimate application for thecomposite material, the porosity must be sufficient to allow at leastsome of the thermoplastic material of layer 29 and/or substrate materialof layer 27 penetrate the pores of the layer 28 such that direct bondingoccurs between layers 27 and 29, respectively.

While the porous layer 28 is generally a separate component prior toprocessing the composite, it should be recognized by those skilled inthe art that the porous layer can be partially embedded into either thethermoplastic material or the substrate as shown in FIG. 3 prior toforming the composite.

The third layer 29 of the composite is formed of a thermoplasticmaterial having a static coefficient of friction of less than about 0.25at 23° C. as measured against chromium plated steel. The thermoplasticmaterial is preferably ultra-high molecular weight polyethylene (UHMWPE)having an average thickness between about 0.2 mm and 10 cm. Ultra-highmolecular weight polyethylenes useful in accordance with the teachingsof the present invention are available from a number of commercialsuppliers such Westlake Corporation of Lenni, Pa. Particularly useful isWestlake's fabric backed, static-reduced UHMWPE. For certainapplications, it may be desirable to include additives to the ultra highmolecular weight polyethylene such as carbon black to make the materialelectrically conductive, thus reducing static buildup.

FIG. 2 is a cross-section of a composite formed from the above describedcomponents. More particularly, the illustrated composite includes aporous layer 28 impregnated by the cured epoxy resin of the substrateand the thermoplastic layer 29. While traditionally there is asignificant amount of difficulty in bonding UHMWPE to other materials,and failure at the bond interface 18 would be expected as will bedescribed in greater detail below, surprisingly testing to date hasfailed to show a failure along the UHMWPE/substrate interface 18.

Shown in FIGS. 3 and 4 are alternative embodiments of the compositematerial wherein the substrate layer 27 c is formed of steel or anothermetal. Disposed on the surface of the substrate is a porous layer 28. Inaddition to natural, synthetic or carbon fibers, the porous layer 28 mayalso be formed from metallic fibers or formed by powder metallurgicaltechniques. As with the embodiment of FIG. 1, the porous layer 28 can bejoined to the metallic substrate 27 c layer prior to formation of thecomposite by use of adhesives.

FIGS. 5 a-5 e, by way of non-limiting example, illustrate formation andprocessing of a composite material in accordance with the teachings ofthe present invention. Disposed on a mold plate or tool 34 is uncuredreinforced epoxy resin based substrate 27. Optionally, but preferably,interposed between the substrate and the mold is a release film 35. Alayer of porous material 28 is disposed on the uncured substrate 27 witha layer of thermoplastic material or UHMWPE 29 having a relatively lowcoefficient of friction disposed thereon. Another layer of release film35 is optionally disposed over the thermoplastic layer.

To form the composite, a vacuum is applied to the construct. The vacuummay be an integral part of the mold or optionally can be in the form ofa vacuum bag 33 having a vacuum line 36 coupled thereto whereby thevacuum bag encapsulates the mold tool. The entire assembly is processedto produce the finished part as is shown in FIG. 5.

FIG. 6 shows a typical autoclave assembly for use in an alternate methodof formation of the current invention. The autoclave wall 50, which actsas a pressure vessel and insulator for the air within the autoclaveassists in the curing of the epoxy and facilitates removal of airbetween the layers. Disposed within the autoclave wall 50 is a pressureinlet 51, which is used to bring pressurized air into the autoclave toassist in processing the construct 28. Further disposed in the autoclavewall 50 is a vacuum outlet 52 for pulling gases out of the vacuum bagassembly 33 as described below.

Within the autoclave wall 50 is a mold base plate 54 over which thematerial is shaped. A flat base 54 is shown, but it is envisioned thatthe mold base plate 54 can take any shape necessary. Disposed on top ofthe mold base plate 54 is the construct 58, including substrate 27,porous layer 28, and UHMWPE layer 29, as previously described.

As is seen in FIG. 7, disposed between the construct 58 and the moldbase plate 54 is a porous release film 35 which allows the material tobe removed from the base plate 54 after processing. Further shown withinthe vacuum bag 33 is an amount of bleeder cloth 56 which functions toabsorb excess epoxy ejected during the process. Although not necessary,it is possible to use a pressure plate 57 to further define the shape ofthe construct 58. Disposed between the pressure plate 57 and theconstruct 58 is a non-porous release film 59 which assists in theseparation of the pressure plate 57 and the composite construct 58. Thevacuum bag 33 is sealed to the mold plate by using a sealant 37. Vacuumoutlets 52 are coupled to the cavity 60 formed by the vacuum bag 33.During the processing of the composite material, heat and pressure areapplied in the autoclave and vacuum is drawn through the vacuum outletport 52.

Those skilled in the art will see that there are many uses of thecomposites produced in accordance with the teachings of this invention.Industries which will benefit from the use of these materials include,but are not limited to, the biomedical, transportation, and conveyorindustries. By way of non-limiting examples, FIGS. 8-25 representcomponents in the food production conveyor industry utilizing the broadteachings of the present invention.

FIGS. 8-10 represent a vibratory pan 72 for use in cereal productionutilizing the composite material 26 of the present invention. As can beseen with reference to FIG. 8 a, which is a magnified view of a crosssection piece of the vibratory pan 72. Upon formation, the vibratory pan72 includes a layer of static reduced UHMWPE, a plastic material whichhas been FDA approved for food contact, and eight layers of 3×3 twillcarbon fiber reinforcement in a 2-part epoxy resin matrix. The staticdissipation by the electrically conductive UHMWPE greatly reduces fineparticle buildup on the surfaces of the vibratory pan 72 during foodproduction. The vibratory pan 72 has a bottom horizontal surface 71 andcoupled depending sides 73. In this application, the weight of theUHMWPE inclusive components compared to the stainless steel, thematerial normally used to form vibrating parts, is greatly reduced. e.g.a weight savings of at least 50%. If desired, reinforcing ribs 74 asshown in FIG. 9 can be incorporated into the composite structure. Uponcoupling the vibratory pan to a driving apparatus 75 as shown in FIG.10, the pan is ready for use.

Normal forced outages because of food product buildup in stainless steelpans is generally reduced and therefore, production is increased.Vibratory pans 72 made of the material 26 further see a significantreduction in the amount of sanitation time needed. One particularbenefit of the UHMWPE layer 29 in a vibratory pan 72, as used in cerealprocessing application, is the almost 100% elimination of sugar coatingsand marbits dust. Furthermore, raisins and other dried fruits build upis greatly reduced. The elimination of fine particles in the vibratorypan 72 is a significant benefit to the food handling industry. Fineparticles which often release after a significant build up cause bags toblow out or an excessive amount of fine particles to be in a product.Because of the static discharging capability of the UHMWPE layer 29,which is electrically grounded, metal detectors which are used to testthe integrity of the food stream can be utilized more effectively.

FIGS. 11 and 12 show coating drums 77 made with the composite material26 in accordance with the present invention. As shown more clearly inFIG. 12 a, the coating drum 77 includes a construction, which includes alayer of UHMWPE 29 on a reinforced composite substrate layer 27. Byproviding a composite construction having an interior layer of UHMWPE29, there is provided an extremely cost effective way to decrease andreduce product build up in a drum's interior 78. Preferably, the druminterior 78 includes a plurality of paddles 79 also having an exposedUHMWPE layer 29, which assist in the coating of food products. Thesedrums are light weight and further show a benefit of havingsignificantly reduced expansion or contraction due to the lowcoefficient of expansion of the composite. The reduced coefficient ofexpansion significantly aids in the line set up of the conveyor system.The coating drums 77 preferably have an interior UHMWPE layer 29 whichis FDA approved in either a natural or anti-static grade.

FIG. 13 represents an elevator lift bucket 80 using the composite 26 ofthe present invention. The elevator lift bucket 80 made using thecomposite structure including a UHMWPE layer 29 and reinforced substratelayer 27, as illustrated in FIG. 13 a, is much stronger thanconventional polypropylene models. The end plates 81, 82 of the bucket80 are removable in case there is a jam because of chain wear in thesystem. As such, the entire bucket 80 need not be thrown away andgenerally only the end plates 81 and 82 need be replaced. Again, theexposed interior surface 83 of the bucket 80 is preferably a UHMWPElayer 29. Raisins, sugar coated cereals, marshmallows, and cracker finesdo not build up. As cleaning solutions do not affect the material,sanitation time is greatly reduced over standard polypropylene elevatorlift buckets 80.

FIGS. 14-16 represent scale hoppers 84 utilizing composite materials 26of the current invention. Ishida-style scale hoppers 84 having doors 85made from the composite material shown in FIG. 16 a as including UHMWPElayer 29 and reinforced substrate 27 provide a number of benefits. Oneof which is a significant decrease in the amount of noise the productrushing through the hopper 84 produces. This is a significant ergonomicbenefit for plant operations. Furthermore, as with other products usingthis composite material 26, there is minimal product build up. Thematerial will not stress crack and is easily cleaned.

FIGS. 17-19 represent blending hoppers 86, the housings of which arenormally made of stainless steel. The hopper 86, and particularly thehopper housing 88, are made of the composite material 26 which preventsraisins, for example, from clumping together when being blended withother food products such as cereal flakes. The inherent nature of theblending hopper 86 normally leads to a significant amount of materialbuild up and thus requires frequent cleaning. As with the otherapplications using the composite material of the present invention,there is a significant reduction of fines.

FIGS. 20 and 21 represent the use of the composite material 26 inbagging hoppers 87. These hoppers 87 have shown significant resistanceto stress cracks and resistance fines build up, particularly thoseresulting from sugar coated flakes which are particularly problematic inthe cereal production industry. The bagging hoppers 87 made of thismaterial represent a significant weight reduction and are easily cleanedand sterilized. FIG. 21 represents a bag hopper 87 having an integralregulator sleeve 91.

FIG. 22 represents a static reduced UHMWPE NuCon demount rotary valve 90using the composite material 26. The use of the static reduced UHMWPEcomponents which are FDA approved greatly reduced fine particle build upwithin the valve. Also eliminated is the risk of static shock whenworkers come into contact with the components during production. As withthe other applications, the weight of the UHMWPE coated components isgreatly reduced when compared to stainless steel. Sanitation time isreduced as the UHMWPE is chemically resistant.

FIGS. 23-25 represent a raisin let down transition 92 for the cerealindustry using the composite material 26 to make the tube 61. Originallythese units were made of stainless steel and included two Teflon coatedproximity sensors 94 similar to those shown. However, due to productbuild up within the raisin and let down transition, the sensing systemshave proven to be ineffective. Further, the sensors of prior artembodiments tend to require cleaning several times a day. Thus, byforming at least the food transporting components of the let downtransition from the composite material 26, the sensors tend to workbetter and require fewer cleanings.

The food transporting portion of the let down transition is generallyformed by a square tube 95. Furthermore, because of the polymer materialof the current invention, proximity sensors are able to be positionedoutside of the unit to allow access to the controls and eliminateproblems associated with having the sensors within the production flow,which is necessary in metallic transitions.

By way of non-limiting example, a preferred method for producing acomposite in accordance with the invention will now be described withreference to the figures, including FIGS. 1-7 in particular. Productionof the composite component which has a 3×3 twill carbon reinforcementwoven layer 28 embedded with an epoxy resin substrate 27 is prepared bythe following steps:

1. Cut substrate material and fabric backed UHMWPE to size and shape(including any add-on pieces).

2. Form any weldments or add-ons required. For example, bottom corners,offset arms for linkage attachment, tabs for linkage attachment, andadded material thickness to accommodate mounting or linkage attachment.

3. Lay-up the substrate 27 onto the base 34 using the proper forms,molds, or other means to hold the uncured laminate in its correct shape.

4. Place fabric backed UHMWPE onto lay-up with fabric side down.

5. Place lay-up in vacuum bag and draw vacuum.

-   -   a) Draw a continuous vacuum of 25-30 In./Hg until bag is        completely drawn down around part(s)    -   b) After bag is completely drawn down set vacuum to AUTO        (approximately 20-22 In./Hg)    -   c) Leave lay-up in bag for 24 hours to achieve full cure of        epoxy-resin

6. Trim away excess epoxy and fabric.

After forming the composite, certain post process steps may be requiredto form a commercial product. For example, the post processing mayinvolve:

-   -   a) Covering the UHMWPE with protective layer;    -   b) Sanding the composite surfaces (only) with 36-80 grit        sandpaper and filling any surface defects with epoxy and        micro-balloon putty (407 micro fillers) and re-sanding;    -   c) Spraying a primer such as U.S. Paint-base #D8008 and        Converter #D3018 on non-UHMWPE composite surfaces;    -   d) Sanding the primed surfaces with 80-180-220 grit sandpaper.        Fill any surface defects with primer thickened with micro        balloons and re-priming; and    -   e) Spraying a color top coat such as U.S. Paint—Awl-Grip, Flat        Black, #G2002, Converter-Awl-Cat #2 G3010 on to non-UHMWPE        layers.

Thereafter, the peel protective paper coating is pulled off of theUHMWPE, any surfaces needing touch-up are painted, the surfaces are thencleaned, and the composite is packed for shipment. As previouslymentioned, the presence of heat from an exothermic curing reaction ofthe substrate 27 may assist in the bonding of the UHMWPE layer 29 to theporous layer 28. It is envisioned that heat from non-reaction sourcesmay be applied during compression to assist the bonding of thethermoplastic layer 29 to the porous layer 28.

Following essentially the same steps described above, various foodmulti-layer processing apparatuses or components having cylindricalconfigurations thereof can be manufactured. Collar assembly, formingtube assembly, and rotating drum are formed using processes applicablefor forming tubes. These tubes can have a layer of UHMWPE on both theinterior and exterior surfaces of the component. The Formation of theforming tube is as follows:

-   -   a) Cut ⅛″ SD-FDA GB material to proper size and shape to form        I.D. of tube.    -   b) Weld ⅛″ SD-FDA GB into tubular shape.    -   c) Lay up fiber filament tube with ten (10) layers of woven        carbon fiber mat and epoxy resin to form middle section of        forming tube “Sandwich”. The I.D. of the filament tube must        match the O.D. of the ⅛″ SD-FDA GB tube from step 1.    -   d) Cut another piece of ⅛″ SD-FDA GB material to proper size and        shape to form O.D. of tube.    -   e) Attach part from step 2 to inside of filament tube from step        3.    -   f) Attach part from step 4 to O.D. of filament tube to form        complete    -   g) Attach add-ons.    -   h) Seal seams, edges, etc. as necessary.

The process for forming the collar assembly is as follows:

-   -   a) Cut ⅛″ SD-FDA GB material to proper size and shape for collar        hood.    -   b) Apply carbon fiber matt and epoxy to hood piece with hood        piece held into a form of the desired shape.    -   c) Apply ⅛″ SD-FDA GB material to backside of hood lay up to        form “Sandwich” construction.    -   d) Repeat steps a-c to form tubular part of collar assembly.    -   e) Attach tubular section to hood piece.    -   f) Attach add-ons.    -   g) Seal seams, edges, etc. as necessary.

Generally flat components such as scale buckets and/or doors can alsohave a layer of UHMWPE on both the interior and exterior surfaces of thecomponent. The formation of the Baseplate is as follows:

-   -   a) Lay up “Sandwich” construction flat blank.        -   One (1) piece ⅛″ SD-FDA GB        -   ½″ carbon fiber matt and epoxy        -   One (1) piece ⅛″ SD-FDA GB    -   b) Cut “Sandwich” construction flat blank to proper size and        shape.    -   c) Attach add-ons.    -   d) Seal seams, edges, etc. as necessary.

The formation of the scale buckets and/or doors are as follows:

-   -   a) Lay up “Sandwich” flat blank piece.        -   One (1) layer ⅛″ glass-backed UHMWPE.        -   Four (4) layers of carbon fiber matt and epoxy.        -   One (1) layer ⅛″ glass-backed UHMWPE    -   b) Cut “Sandwich” lay up to proper size and shape.    -   c) Bend and weld respective pieces to proper size and shape        using forms as necessary.    -   d) Attach add-ons.    -   e) Seal seams, edges, etc. as necessary.

As shown in FIGS. 26 and 27, the substrate 27 can form integral flangeor box support structures. These structures can be formed of layershaving differing properties 97 and 96. In this regard, the box structurecan have incorporated metal or composite members.

Alternatively, the composite material can be formed of a layer of UHMWPEhaving a knit fabric porous layer. In this regard, as shown in FIG. 28,the knit layer can be a three-dimensional fabric produced by adouble-needle 22-gauge bed warp-knitting machine using GB1 and GB2 guidebars. As shown, the guide bars GB1 and GB2 interact with the stitch combbars 100 and 102. These guide bars 100 and 102 interact with the latchneedle bars 104 and 106 which interact with the knock-over bars 108 and110 and knock-over plates 112 and 114 to form the knit fabric as isknown. The knit fabric can be formed of glass, basalt, or carbon fibersusing a loft-type loop structure. Optionally, the knit can be aspacer-type fabric formed of two surfaces joined by a pile.

The knit porous layer can be formed of knitted 50-75 and, preferably 68tex glass yard (a mean weight of about 50 to about 75 and, preferably,68 grams per 1000 meters) having a size finish. Optionally, the sizefinish can be silane. It is envisioned that the fibers can be coatedwith other materials to facilitate the bonding of the glass fibers toepoxy resin. The porous layer can be formed of an atlas or tricot knitpatterns or a combination thereof (see FIGS. 29 a and 29 c) formed on an11-gauge knitting machine. Optionally, the mean stitch length can bebetween about 0.8 and about 2 mm, and specifically between about 1 andabout 1.5 mm, and most particularly about 1.2 mm.

To produce the above-disclosed material, UHMWPE powder having a meandiameter of between 0.1 and 1 mm is placed within a heat press incontact with a layer of knit material as described above. In thisregard, the knit material can be placed beneath or on top of the UHMWPEpowder. The powder and knit material are then compressed under heat andpressure so that between about 40% and about 60% of the knit material isimpregnated within a monolithic UHMWPE sheet.

The powder and knit porous layer can be compressed at temperatures ofbetween about 375-390° F. to (1000 to 1500 psi). Optionally, the powderUHMWPE can be heated and compressed for approximately 1 hour per 10 mmof powder thickness. As shown in FIG. 2, the knit porous layer ismechanically coupled to the monolithic sheet of UHMWPE. Thisconstruction can then be bonded to metal or epoxy polymers as describedin detail above. It is specifically envisioned that the construction canbe coupled to uncured reinforced prepreg epoxy material. As describedabove, the uncured material can then be subjected to vacuum and heat soas to allow the uncured material to flow into the knit material so as tobe in direct contact with the UHMWPE. Alternatively, the UHMWPE sheetand knit porous layer can be bonded to a metallic layer using adhesivessuch as epoxy adhesive. This adhesive will be positioned so as to placethe adhesive in contact with the monolithic UHMWPE layer.

It is specifically envisioned that the size of the UHMWPE particles willbe large enough so that they will not pass completely through thematerial. It is, therefore, envisioned that the specific pore size ofthe knit material as well as the size of the UHMWPE powder can beadjusted so as to allow the ultra-high molecular weight polyethylene toonly flow about 50% through the knit porous layer during the compressivewelding process.

FIGS. 30 a and 30 b represent a boat hull 120 utilizing a compositematerial 122 described above. In this regard, it is envisioned that amaterial 122 utilizing a knit porous layer and an UHMWPE layer can becoupled to a portion of a water craft. The material 122 can be coupledto a portion of or the whole underside of the hull. Additionally, thematerial 122 can be coupled to loading top surfaces of the water craft.The material 122 can be coupled to a metal, composite, or wood hullusing epoxy. Additionally, the material can be coupled to the hull 120using the composite construction techniques described above.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with particular examples thereof, the truescope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification, and following claims.

1. A composite material applicable to form a structure, the compositecomprising: a knit porous layer partially disposed within said substratematerial forming a mechanical bond therebetween; and a UHMWPEthermoplastic layer having an average thickness of greater than 1.0 mmand less than about 10.0 mm which is in contact with said porous layer;wherein said UHMWPE thermoplastic layer penetrates only a portion ofsaid porous layer.
 2. The composite of claim 1 whereby upon joining saidlayers said knit porous layer becomes at least partially embedded insaid UHMWPE thermoplastic.
 3. The composite of claim 1 furthercomprising a substrate including a layer formed from a thermosetmaterial.
 4. The composite of claim 3 wherein said substrate layerformed from a thermoset material is selected from the group consistingof reinforced epoxy composite, carbon reinforced epoxy composite, glassfiber reinforced epoxy composite, synthetic fiber reinforced epoxycomposite, and woven fabric fiber reinforced epoxy composite.
 5. Thecomposite of claim 1 wherein said knit porous layer comprises glass yarnhaving a weight between about 50 and about 75 grams per 1000 meters. 6.The composite of claim 5 wherein said knit porous layer comprises glassyarn having a weight of about 68 grams per 1000 meters.
 7. The compositeof claim 1 wherein said knit porous layer comprises a yarn knit into oneof an altas knit, tricot knit, and combinations thereof.
 8. Thecomposite of claim 7 wherein said knit porous layer comprises a knitmaterial having a stitch length between 0.8 and 1.5 mm.
 9. The compositeof claim 1 wherein said knit porous layer comprises a glass yarn havinga size finish.
 10. The composite of claim 1 wherein said knit porouslayer defines pores of a predetermined size.
 11. The composite of claim1 wherein said knit porous layer comprises a loft knit structure.
 12. Acomposite material comprising: a substrate including a layer formed froma material; a knit porous layer partially disposed within said substratelayer forming a mechanical bond therebetween; and a UHMWPE layer havingan average thickness of greater than 1.0 mm and less than about 10.0 mmdisposed upon said porous layer, wherein said porous layer is at leastpartially disposed within said UHMWPE layer and said UHMWPE layer isdirectly bonded to the substrate layer formed from a non-UHMWPE materialthrough said knit porous layer.
 13. The composite of claim 12 wherebyupon joining said layers said knit porous layer is more than 50%embedded in said UHMWPE.
 14. The composite material of claim 12 whereinsaid substrate layer is selected from the group consisting essentiallyof reinforced epoxy composite, metal, carbon reinforced epoxy composite,glass fiber reinforced epoxy composite, synthetic fiber reinforced epoxycomposite, and woven fabric fiber reinforced epoxy composite.
 15. Thecomposite material of claim 12 further comprising a pair of dependingsidewalls, said UHMWPE layer disposed on said sidewalls.
 16. Thecomposite material of claim 12 wherein said composite material defines avibratory pan.
 17. The composite of claim 12 wherein said knit porouslayer comprises glass yarn having a weight between about 50 and about 75grams per 1000 meters.
 18. The composite of claim 17 wherein said knitporous layer comprises glass yarn having a weight of about 68 grams per1000 meters.
 19. The composite of claim 12 wherein said knit porouslayer comprises a yard knit into one of an altas knit, tricot knit, andcombinations thereof.
 20. The composite of claim 19 wherein said knitporous layer comprises a knit material having a stitch length betweenabout 0.8 and about 1.5 mm. 21-34. (canceled)